1. Field of the Invention
The present invention relates to a chemically amplified resist composition, and more particularly, to a photosensitive polymer having a phenyl ring and a lactone group, and a resist composition comprising the same.
2. Description of the Related Art
As processes for manufacturing semiconductor devices become more complicated and the integration density of semiconductor devices increases, the need to form finer patterns becomes more pronounced. Furthermore, with regard to semiconductor memory devices having a capacity of 1 Gigabit or more, a pattern size having a design rule of 0.2 xcexcm or less is needed. Accordingly, there are limitations in forming such fine patterns using conventional photoresist materials using a KrF excimer laser (248 nm). For this reason, a lithography technique using a new exposure light source, the ArF excimer laser (193 nm), has emerged.
However, a resist material suitable for use in lithography with the ArF excimer laser causes many problems in practical use, compared with a conventional resist material. The most serious problem is the collapse of patterns as the aspect ratio increases. Therefore, the thickness of the resist layer must be lowered. However, there is a limitation in the resistance of the resist layer to dry etching, so that many problems arise in actually forming patterns.
In order to increase resistance to dry etching, polymers introducing a phenyl group or an adamantly group have been suggested. However, these polymers have poor hydrophilic properties, and thus adhesive properties are not good. As a result, many problems can occur in a process using a resist layer such as lifting.
It is a first feature of the present invention to provide a photosensitive polymer having a structure capable of providing superior lithography performance when the photosensitive polymer is used for a resist material.
It is a second feature of the present invention to provide a resist composition capable of intensifying resistance to dry etching, and improving adhesive properties.
In accordance with one aspect of the present invention, there is provided a photosensitive polymer including a monomer unit having a group indicated by the following formula (I). 
In more specific embodiments, the photosensitive polymer has the following structural formula: 
where R1, R2, and R3 are independently a hydrogen atom or an alkyl group, l/(l+m+n)=about 0.2-0.5, m/(l+m+n)=about 0-0.5, and n/(l+m+n)=about 0.4-0.7.
In accordance with another aspect of the present invention, there is provided a monomer unit having a group indicated by the following formula (III): 
In more specific embodiments, the photosensitive polymer has the following structural formula (IV): 
where R4, R5, and R6 are independently a hydrogen atom or an alkyl group, l/(l+m+n)=about 0.2-0.5, m/(l+m+n)=about 0-0.5, and n/(l+m+n)=about 0.4-0.7.
According to a further aspect of the present invention, there is provided a resist composition comprising (a) a photosensitive polymer including a monomer unit having a group indicated by the formula (I) above, and (b) a photoacid generator (PAG).
According to still another aspect of the present invention, there is provided a resist composition that comprises (a) a photosensitive polymer including a monomer unit having a group indicated by the formula (III) above, and (b) a PAG.
Other features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description. It is to be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Many changes and modifications may be made without departing from the spirit thereof, and the invention includes all such modifications.
Priority Korean Patent Application No. 00-79190, filed Dec. 20, 2000, is hereby incorporated in its entirety by reference.
In particular embodiments, the substituents are R1-R6 can be alkyl groups having 1 to 6 carbon atoms.
The weight average molecular weight of the photosensitive polymer included in the resist composition according to the present invention preferably is about 1,000 to about 100,000.
The amount of the PAG preferably is in the range of about 1 to about 15% by weight based on the weight of the photosensitive polymer. Preferably, the PAG comprises at least one selected from the group consisting of triarysulfonium salts, diaryliodonium salts, sulfonates, and mixtures thereof. More particularly, the PAG comprises triphenylsulfonium triflate, triphenylsulfonium antimonate, diphenyliodonium triflate, diphenyliodonium antimonate, methoxydiphenyliodonium triflate, di-t-butyldiphenyliodonium triflate, 2,6-dinitrobenzyl sulfonates, pyrogallol tris(alkylsulfonates), N-hydroxysuccinimide triflate, norbornene dicarboximide triflate, triphenylsulfonium nonaflate, diphenyliodonium nonaflate, methoxydiphenyliodonium nonaflate, di-t-butyldiphenyliodonium nonaflate, N-hydroxysuccinimide nonaflate, norbornene dicarboximide nonaflate, triphenylsulfonium perfluorooctanesulfonate (PFOS), diphenyliodonium PFOS, methoxydiphenyliodonium PFOS, di-t-butyldiphenyliodonium PFOS, N-hydroxysuccinimide PFOS, norbornene dicarboximide PFOS, or a mixture of these materials.
The resist composition of the present invention can further comprise an organic base. The amount of the organic base preferably is in the range of about 0.01 to about 2.0% by weight based on the weight of the photosensitive polymer. Preferably, the organic base comprises a tertiary amine compound or a mixture of at least two tertiary amine compounds. More particularly, the organic base comprises triethylamine, triisobutylamine, triisooctylamine, triisodecylamine, diethanolamine, triethanolamine or a mixture of these compounds.
The photosensitive polymer according to the present invention includes a material having a phenyl ring and a lactone group. Therefore, the resist composition comprising such a photosensitive polymer not only provides sufficient resistance to dry etching but also has excellent adhesive properties.
The features and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof.